Genome-wide identification of GRF transcription factors and their expression profile in stem meristem of broomcorn millet (Panicum miliaceum L.).

To understand the genome-wide information of the GRF family genes in broomcorn millet and their expression profile in the vegetative meristems, bioinformatic methods and transcriptome sequencing were used to analyze the characteristics, physical and chemical properties, phylogenetic relationship, chromosome distribution, gene structure, cis-acting elements and expression profile in stem meristem for the GRF family members. The results showed that the GRF gene family of millet contains 21 members, and the PmGRF gene is unevenly distributed on 12 chromosomes. The lengths of PmGRF proteins vary from 224 to 618 amino acids, and the isoelectric points are between 4.93-9.69. Each member of the family has 1-4 introns and 2-5 exons. The protein PmGRF13 is localized in both the nucleus and chloroplast, and the rest PmGRF proteins are located in the nucleus. Phylogenetic analysis showed that the 21 GRF genes were divided into 4 subfamilies (A,B,C and D) in broomcorn millet. The analysis of cis-acting elements showed that there were many cis-acting elements involved in light response, hormone response, drought induction, low temperature response and other environmental stress responses in the 2000 bp sequence upstream of the GRF genes. Transcriptome sequencing and qRT-PCR analyses showed that the expression levels of PmGRF3 and PmGRF12 in the dwarf variety Zhang778 were significantly higher than those of the tall variety Longmi12 in the internode and node meristems at the jointing stage, while the expression patterns of PmGRF4, PmGRF16 and PmGRF21 were reverse. In addition, the expression levels of PmGRF2 and PmGRF5 in the internode of Zhang778 were significantly higher than Longmi12. The other GRF genes were not or insignificantly expressed. These results indicated that seven genes, PmGRF2, PmGRF3, PmGRF4, PmGRF5, PmGRF12, PmGRF16 and PmGRF21, were related to the formation of plant height in broomcorn millet.

[Effects of Mulching and Slow-release Fertilizer Application Reduction on Soil Microbial Community Structure in Rapeseed Field Under Two Different Rainfall Conditions].

In order to investigate the effects of furrow and ridge rainwater harvesting, straw mulching, and reduced and slow-release fertilizer on soil microbial community structure of rapeseed, a two-year field study was conducted in rainy (2016-2017) and drought (2017-2018) seasons, which included three cultivation patterns:1 conventional flat planting, 2 straw mulching, and 3 ridge-furrow rainfall harvesting system and four fertilization patterns:1 conventional fertilization (100% of the amount), 2 reduced slow-release fertilizer Ⅰ (80% of the amount), 3 reduced slow-release fertilizer Ⅱ (60% of the amount), and 4 no fertilizer. The results indicated that it was rainy in 2016-2017, with seasonal drought during the nutritional growth stage in 2017-2018. The two technologies (straw mulching+80% slow-release fertilizer, J80 and ridge-furrow rainfall harvesting system+80% slow-release fertilizer, M80) were beneficial to boost the soil microbial activity. J80 and M80 increased the microbial biomass carbon by 9.94% and 10.32% and microbial biomass nitrogen by 2.38% and 1.19%, respectively, compared with that of the local cultivation pattern under two different climate conditions. The total amount of microbial phospholipid fatty acid (PLFA) decreased by 30.75% in the rainy year compared with that in the drought year, and mulching technology could effectively increase the total amount of soil PLFA. The PLFA contents of soil bacteria and fungi in the rainy year were 33.67% and 53.21%, respectively, lower than those in the drought year. However, the PLFA content of actinomycetes increased by 13.04%. Microbial communities were sensitive to abnormal precipitation. The bacteria/fungi ratio increased in rainy weather. The drought climate heighted the ratio of straight chain saturated fatty acid/straight chain monounsaturated fatty acid and straight chain monounsaturated fatty acid/cyclopropane acid. In conclusion, adopting the optimal cultivation technologies can stabilize the soil microenvironment under abnormal precipitation, relieve water and nutrient stress, and provide an effective means for rapeseed sustainable development.